JPH0622589B2 - Method for manufacturing antibacterial molded products - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a molded article by a coating method, and more specifically, a molded article having antibacterial properties is produced by a coating method. It is about the method.

(Prior Art) Examples of raw material latices used for producing rubber products by a coating method such as a dipping method include natural rubber latices, chloroprene latices, and butadiene-styrene copolymer latices.

Natural rubber latex is a milky white sap that flows out when a rubber shaft is cut, with 0.3 to 1.0% of ammonia being added as a preservative, and the composition of this latex is 35 to 40% of rubber hydrocarbons. In addition to including%,
Consists of about 2% protein, other 1% or less small amount of fatty acid or its ester, sterol, complex lipid, saccharide, inorganic substance, enzyme and the like. Therefore, in natural rubber latex, the protein, which is an ampholyte contained in the component, plays a role of a kind of protective colloid by adsorbing on the surface of the rubber particles, and assists the stable floating dispersion of the latex particles. That is, since these rubber particles have a charge in the weakly acidic and alkaline regions, they are stably dispersed without agglomeration due to electrostatic repulsion between the rubber particles. The fresh lattex shed from the rubber tree is an almost neutral (pH 7.0-7.2), relatively unstable emulsion. That is, when the latex is exposed to the air in the tropics, it is rapidly rancid by the action of bacteria, the pH becomes about 5 in 12 to 14 hours, and spontaneous coagulation occurs. This is because the Latex water phase contains extremely convenient substances such as proteins, salts, and sugars for the propagation of bacteria, so that the bacteria propagate extremely rapidly. Therefore, it is necessary to add an appropriate preservative at an early stage where the rancidity does not progress as much as possible, but as the preservative, ammonia is the most suitable as a preservative to neutralize the acid and repel bacteria to prevent their reproduction. Has been done. Since ammonia is usually added in an amount of 0.3 to 1.0%, the pH of the latex is kept at least 9 or more, and usually 10 or more alkaline. JJ K 6381 (1982), which is currently established as the Japanese Industrial Standard for Natural Rubber Latex, was established along this line.

Usually, the compounded latex used in the coating method is a mixture of the above-mentioned raw material latexes, if necessary, with a vulcanizing agent, a vulcanization accelerator, a filler, a softening agent, an antiaging agent, a pH adjusting agent and the like. These are kept or adjusted to remain alkaline even after blending. Therefore, the currently used natural rubber latices are based on negatively charged anionic latices, and almost all kinds of coated molded products are manufactured from them.

Examples of the synthetic rubber latex include homopolymers or copolymers of vinyl-based monomers, homopolymers or copolymers of diene-based monomers, copolymers of the above vinyl-based monomers and diene-based monomers, and other functional compounds. Epoxide group, amino group, carboxyl group, acid anhydride group, hydroxyl group, amide group, N-methylolamide group,
Examples thereof include those containing, as a main component, a copolymer of a vinyl-based monomer having an isocyanate group or the like and the above various monomers.

The molding method of the latex is, for example, a coating method such as a dipping method, a casting method, an extrusion method, a form laver manufacturing method, a fiber surface processing method, a fiber adhesion method, or the like. In addition, there are problems with the special manufacturing technology as described below. In other words, in the dip molding method, the latex is filled in the dipping tank, the dipping die is dipped into the dipping tank, and then the latex is attached to the dipping die by pulling it up. In contrast, the latex stored in the dipping tank is overwhelmingly larger, and the economic loss when the latex is gelled in the dipping tank is immeasurable.

Conventionally, the most effective method for imparting a sustained antibacterial activity to a medical device is to disperse the antibacterial agent so that the antibacterial agent having a certain concentration or more is retained in or on the surface of the base material during the use process. So-called matrix devices are considered as systems.

On the other hand, it is known that heavy metals such as gold, silver, copper, and zinc, and these metal compounds have strong bactericidal effects against microorganisms such as bacteria and fungi at extremely minute concentrations in the state of metal ions. , Called oligo dynamism.

Generally, since the solubility of silver compounds and silver salts in water is low, the silver concentration in the base material becomes very low when compounded in a latex in a solution state. In addition, in order to increase the silver concentration in the base material, for example, when silver nitrate, which has high water solubility, was added to the latex as an aqueous solution, the reason for this is not clear, but the latex can be stably suspended in the aqueous solution. It destroys the existing system and causes agglomeration, making it impossible to obtain a stable latex composition.

From the viewpoints described above, we propose the above metal, especially the one that has the metal body deposited on the base material, or the tool in which the metal is dispersed and mixed in the base material, by utilizing the oligodynamic of the silver compound. Has been done.

For example, Japanese Unexamined Patent Publication No. 52-62996 proposes a catheter in which a flexible tubular body is coated with a metal body having oligodynamics, or a ring or net made of the metal body. However, the operation of depositing a metal body on the surface of a molded catheter is always troublesome and complicated, and the production efficiency at the actual manufacturing site is low.

Further, JP-A-59-218517 discloses a catheter having antimicrobial activity by pulverizing an antimicrobial metal compound into particles within 30 μm, dispersing the compound in a suspension capable of forming a catheter, and curing it. A method of forming is described. However, it is necessary to add a so-called surfactant in order to prevent a re-aggregation of the particles of the crushed metal compound and to maintain a stable particle state in the step of crushing the metal compound into particles within 30 μm. The cost will increase.

As described above, in order to manufacture a molded product of a type having an antibacterial property by itself using oligo dynamism, a step of molding the molded product as described above and then applying a metal body to the surface of the molded product or It is necessary to pulverize the metal compound into fine particles and disperse them in a suspension, which is a problem because the production efficiency is low and the manufacturing cost is increased.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for producing an antibacterial molded product in which the molded product itself has sustained antibacterial activity.

Another object of the present invention is to provide a method for producing an antibacterial molded product with a simple operation and industrially with high productivity.

Another object of the present invention is to provide a method for stably producing an antibacterial molded article by using a coating liquid composed of a latex composition containing a silver compound.

(Means for Solving Problems) As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a cationic natural rubber latex or a cationic synthetic rubber latex is mixed with a water-soluble silver compound. The inventors have found that a latex composition having excellent stability can be obtained, and that the intended purpose can be achieved by using this composition as a coating liquid, and the present invention has been completed.

That is, the present invention uses a coating liquid composed of natural rubber latex or synthetic rubber latex, and when a molded product is manufactured by a coating method, a water-soluble silver compound is mixed with a cationic natural rubber latex or a cationic synthetic rubber latex as a coating liquid. The gist is a method for producing an antibacterial molded article, which is characterized by using a latex composition.

The natural rubber latex referred to in the present invention means an aqueous solution containing various organic substances and inorganic substances that flow out when a ticket is applied to the bark of a rubber plant as a dispersion medium, and a rubber component as a dispersoid.
PH adjuster, vulcanization killing, vulcanization accelerator, filler, if necessary
This is a latex containing anti-aging agents and coloring agents.
Ordinary latex has no ammonia as a pH adjuster.
It is an anionic latex containing 3% by weight and having a pH adjusted to 9-11. On the other hand, the cationic natural rubber latex used in the present invention includes a so-called acidic latex having a pH of isoelectric point of the protein which is a protective goroid, pH 4.7 or less, preferably 3 or less.
In that state, the rubber particles are stabilized by repulsing each other with a positive charge opposite to that of a normal natural rubber latex. To adjust such acidic latex, for example, ordinary natural rubber latex (solid content of 50 to 6) is used.
0%, pH 9 to 11), and a cationic surfactant or nonionic surfactant is added to the rubber component so as to be about 1 to 5% by weight, and then an appropriate inorganic acid or organic acid is added. PH to 3 or less. Hydrochloric acid and sulfuric acid are preferably used as the inorganic acid, and formic acid, acetic acid, oxalic acid and the like are preferably used as the organic acid.

Examples of the cationic synthetic rubber latex used in the present invention include ethylene, styrene, vinyl acetate, vinyl chloride, vinylidene chloride and acrylonitrile.
(Meth) acrylic acid esters, vinyl pyridine, homopolymers of vinyl monomers such as methyl vinyl ether or their copolymers, butadiene, isoprene, 1,3-pentadiene, 1,5-hexadiene, 1,6-heptadiene, chloroprene Homopolymers of diene-based monomers such as or copolymers thereof, copolymers of the above vinyl-based monomers and diene-based monomers, and other functional groups such as epoxide groups, amino groups, carboxyl groups, acid anhydride groups, hydroxyl groups, amide groups , A copolymer of vinyl monomers having N-methylolamide group, isocyanate group, etc., and the above-mentioned various monomers as a main component, and a cationic surfactant as an emulsifying dispersant are added thereto, which are required. There are nonionic surfactants, cross-linking agents, fillers, softeners, etc. That.

In the present invention, a water-soluble silver compound is used as the antibacterial agent. Suitable water-soluble silver compounds include silver salts and protein silver. The silver salt means a salt formed of silver and an inorganic acid or an organic acid. Specific preferred examples of the silver salt include silver nitrate, silver lactate, silver chlorate, silver fluoride, silver picrate, and the like. Protein silver is a compound of protein and silver, and silver containing 7.5 to 8.5% by weight as silver listed in the Japanese Pharmacopoeia is preferably used.

The term “water-soluble” as used in the present invention means that the solubility in 100 g of distilled water at 20 ° C. is 1.0 g or more, preferably 5.0 g or more.

The preferred amount of the water-soluble silver compound varies depending on its purpose and the type of the silver compound acting, but in general, it is 0.1 to 30% by weight, particularly 0.5 to 10% by weight, based on the solid content of the latex. Preferably there is. If the blending amount exceeds 30% by weight, the strength of the molded product obtained therefrom tends to be inferior, while if it is less than 0.1% by weight, the antibacterial performance becomes difficult to be exhibited, which is not preferable.

The method for preparing the coating liquid in the present invention is not particularly limited as long as each component is uniformly mixed, and various known methods can be used. For example, a method of directly adding an aqueous solution of a water-soluble silver compound, particularly preferably an aqueous solution having a high water-soluble silver compound concentration, to the latex is preferably adopted.

In order to produce a molded product by the method of the present invention, any conventionally known method may be used. For example, as the dipping method, a straight method, a coagulation dipping method (anode method or Teague cohesion method), a heat-sensitive dipping method, an electrodeposition dipping method and the like can be mentioned. As a specific example, when manufacturing a urinary catheter made of natural rubber, the urinary catheter is usually made from natural rubber latex by an immersion molding method, which is one of the coating methods. By specially preparing the compounded natural rubber latex composition, it can be manufactured by the same manufacturing method as the conventional one. Also, when other synthetic rubber latex composition is used as a coating liquid, a semi-finished product made of the same type of base material or a different type of base material is similarly immersed in the coating liquid or sprayed with the semi-finished coating liquid, so-called coating. It can be manufactured by the method.

(Examples) Hereinafter, the present invention will be described more specifically with reference to Examples.

In the examples, “part” means “part by weight”.

Example 1 0.4 part of zinc dimethyldithiocarbamate, 1 part of sulfur, 2.5 parts of zinc white and 1 part of steanoic acid were uniformly dispersed in 100 parts of acidic natural rubber latex (pH 2.8) having a solid content of about 60% by weight. A compounded latex containing natural rubber as a main component (hereinafter referred to as liquid A) was prepared. Solution A above 1
When 10 parts of an aqueous silver nitrate solution (10% by weight) was added to 00 parts under stirring, the latex was not aggregated and a coating solution (1.1% by weight of silver) in which silver nitrate was uniformly dispersed could be obtained.

Using the obtained coating solution, a continuous urinary catheter manufacturing device by a normal dip molding method was used to replenish the weight loss on that day, and continuous production on an industrial scale was carried out. The lattex of No. 3 was able to stably produce a constant quality urinary catheter without producing aggregates.

About the obtained urinary catheter,
An antibacterial activity test was conducted.

That is, the obtained urinary catheter was cut, the section was washed with a 70% ethanol aqueous solution in a sterile environment, ethanol was dried and distilled off, and then the sample bottle was placed with the inner surface facing upward. It was Then, on the inner surface of the section, 200 μl of a bacterial solution obtained by culturing Escherichia coli in Trypticase soyproth overnight at 37 ° C. was placed, sealed, and cultured at 37 ° C. for 18 hours. Then add 0.1% surfactant (Tween
80, Sankei Sangyo) was added to collect the bacterial solution, and the number of surviving bacteria was measured by the colony counting method. As a control, the same operation as above was performed except that the bacterial solution was directly placed on the bottom of the sample bottle.

As a result, the number of bacteria recovered was 0.7% of the control.

The urinary catheter of Example 1 was immersed in water at room temperature for 1 week, dried, and then subjected to an antibacterial activity test by the same method as described above. The number of recovered bacteria was 5.2% of the control. Met.

Comparative Example 1 When 100 parts of anionic natural rubber latex having the same composition as the above-mentioned solution A and a pH of 10.0 was added with an aqueous silver nitrate solution (10% by weight) with stirring, the compounded latex rapidly increased in viscosity and many small aggregates were formed. did.

Using the obtained coating solution, an attempt was made to manufacture a urinary catheter in the same manner as in Example 1. However, the urinary catheter having a uniform surface property was stabilized by increasing the viscosity of the latex and forming a large number of aggregates. Could not be manufactured.

Example 2 Example 1 except that 30 parts of an aqueous protein silver solution (20% by weight) was used instead of 10 parts of an aqueous silver nitrate solution (10% by weight).
When continuous production of a urinary catheter was carried out in the same manner as described in 1., even after one month, the latex in the dipping tank did not generate an agglomerate, and a urinary catheter of constant quality could be stably manufactured.

The obtained urinary catheter was subjected to an anti-corrosion activity test by the same method as in Example 1, and the number of recovered bacteria was 2.3% of the control.

Example 3 Continuous production of a urinary catheter was performed in the same manner as in Example 1 except that 10 parts of an aqueous solution of silver picrate (5% by weight) was used instead of 10 parts of an aqueous solution of silver nitrate (10% by weight).
Even after a month, the latex in the dip tank did not generate aggregates, and a stable quality urinary catheter could be manufactured. About the obtained urinary catheter,
When antibacterial activity tete was carried out by the same method as in Example 1, the number of recovered bacteria was 6.8% of the control.

(Effects of the Invention) According to the present invention, a latex composition in which a water-soluble silver compound is mixed with a cationic natural rubber or a cationic synthetic rubber latex is incorporated into an ordinary production line without requiring any special device or advanced technique. By doing so, it is possible to continuously produce antibacterial molded products having a continuous antibacterial activity on an industrial scale in a stable manner, and its industrial significance is extremely significant.

According to the present invention, for example, molded articles such as medical device tools, sanitary tools, food manufacturing devices or fixtures that have persistent antibacterial properties even during a long-term use process can be manufactured.
Specific examples of such molded products include catheters including urinary catheters, surgical gloves and other bags, finger cots, nipples for baby bottles, ice bags used by patients in hospitals, bags such as urine storage bags. Examples include supply / drainage tubes, sponges, etc. These have antibacterial agents on their surfaces and are extremely effective in preventing infection from bacteria and fungi.

 ─────────────────────────────────────────────────── --Continued from the front page Examiner Misao Takanashi

Claims (3)

[Claims] 1. A latex composition in which a water-soluble silver compound is mixed with a cationic natural rubber latex or a cationic synthetic rubber latex as a coating liquid when a molded product is produced by a coating method using a coating liquid composed of natural rubber latex or synthetic rubber latex. A method for producing an antibacterial molded article, characterized in that a molded article is used. 2. The production method according to claim 1, wherein the water-soluble silver compound is silver nitrate. 3. The production method according to claim 1, wherein the water-soluble silver compound is protein silver.